Process for separating naphthenes



Patented Mar. 24, 1953 BROG SSQEEORS-EBARATING NAPHTHENES FROMQBARAEFIN HYDROCARBONSZ Fredrick D; Jiinach; Richmond Hill; N. Y., assignor 'to Stand'ardDil DevelopmentGompany; acorporation of Delaware No nrawing, Application July is, 1950;, sen-aim; 174,789

1: v Thisinvention relatesrto=theiseparati of drocarbons and" is particularly directed-'- t fi clailnsr ((31.260-666) method of, separating naphthene hydrocarbons from" a mixture. containing naphthenesand parafiinsr It is'known-in the-art to'separate hydrocarbons meansofjsolid adsorbents, such" as carbon or'sil'ica gel; It, *isrgenerally recognized" that the adsorptiveiafiihityof silicagel'andlikeadsorbents for hydrocarbons? varies"with the hydrocarbon ltypeinthe:following"deoreasing'order2 (1) Aromatics (2 Olefins-;- j i (3:) Naphthenes and parafiins.

It is possible' to =u-tilize=this selctive adsorption 'b'yv solid adsorbents-'- to 1 separate aromatics from bl'efin-s; naphthenes and' paraffins andto separate olefins-from' naphthenes and paraflinsr" However,

I the affinityof-=" solid-" adsorbents for naphthenes and for "parafiins*issonearly the same'that it has generally: b'een'monsideredimpractical teattempt to separate naphthenes from parafiinsby seletiveadsorptioni' It has now. been foundjhatsnaphthenes can be separated from parafii'ns by adsorption on silicazgel and other'adsorbents when the adsorbent flail imth'emlassofselective;solvents for; hydrojcarbons; although they do not" appear;to. have been employedsuccessfully for the particular separation ofina 'ahthenesefroinc paraffins. The

mechanism whereby the solid adsorbents are improvediiorwnaphtheneeparafiin separation by the presence offthezsolvent is not known with? oer.- tainty One explanation isathata the SOIVQHtYiII the adsorbed f'state rfunctions as a superior; selec: tive solvent for naphthenes. Another explanation is that the solvent'plugs up those pores in the adsorbent that normally adsorb paraffins.

Whateverthe mechanism ma'yibe; the: invention provides a novelimproved adsorbent, anda new and improved process for= the separation of hydrocarbons The advantages of theinvention will he -better understood from a-Lconsideration of the following experimental data which are given for the sakeof illustration but Without intention of limitingr; the :invention thereto.

EXAMPLE I 373 cc. of an'aromatic-freehydrocarbon ;feed stock boiling-1159250? and. having a. Research octane number" of 66' was" percolatedat, room temperature through -22.foot .column'; 1 inches in diameter filled with 4240 gramsx'of silica: gel containing 20% of the monoethyl ether of diethylenenglycol commonly called Carbitoh In this example and. in, the, other examples reported below, flow. of .the feedstock through the ,gel was maintainedlby, the useiofflisopropyl jalcohol as a chaser,- although this is :not necessary when operating. continuously; The'fi'rst percolated was, foundhto be enrichedl in, paraffihs, and to possess anoctane numberoi-IGO. Thelast50% percolated was increased in naphthenic content and :found: to have an octane number 01570; The following data were-= obtained:

Table I Paraifius (Vol. Percent) Naphthenes (VOL can Research Octane N al I 0 Total 0W1) Total orm s 05 C a Feed 22 36 58 22 20 42 66 Cutl n 27 46 73 14 13 27 Cut 36 1 21 35 56 23 21 44 Cuts 1-36 (blended) .i 26 44 70 16 14 30 60 Cuts 69-70 3 17 29 46 28 26 54 Cuts 37-70 (blended). 19 32 51 26 23 49 70 1 Represents O to l.4%-perco1ated. 1 Represents 49.3 to 50.7 0 percolated. 9 Represents 95.8 to 98.5% percolated.

EXAMPLE II 18.6 cc. of the same feed stock used in Example I was percolated at room temperature through two different 270 cc. batches of silica gel, one batch of silica gel being untreated and the other treated with Carbitol in the ratio of 46.3 grams of Carbitol and 185.3 grams of silica gel with the following results:

Table II Analysis of Last 30% of Percolated Feed, Material Compound Type by Raman Vol.

Percent Without With Carbitol Carbitol n Parafiins 22 23 15 Iso Paraflins 36 35 25 Cyclopentanes. 22 23 31. 5 Cyclohexanes 20 19 28. 5 Ratio of n/isopara-filns 0. 6 0. 7 0. Ratio of CyO lCyCa 1. l l. 2 1.1 Ratio of paraffins to naphthenes 1.4 1.4 0. 7

The above data clearly indicate that pretreatment of silica gel with Carbitol increases the adsorptive affinity of silica gel toward naphthenic hydrocarbons to an important degree.

EXAMPLE III A mixture of 50.2 mol percent of normal heptane in methylcyclohexane was percolated at room temperature through a column of silica gel pre-treated with 25% of various materials. The following comparative data were obtained on the The above data indicate that selective solvents in general increase the selectivity of adsorbents for particular types of hydrocarbons. The data also indicate that ethylene glycol and Carbitol are eminently superior in their ability to increase the adsorptive aflinity of silica gel toward naphthenes and that aniline, acetone, isopropyl alcohol, dimethoxy triglycol also markedly increase this ailinity.

It will be obvious to those skilled in the art that the improved adsorbents of the invention can be utilized either batch-wise or continuously. For

example, in continuous operation the granular or fluidized powdered adsorbent may be passed countercurrent to the feedstock in a tower adsorber, the adsorbent removed from the tower and stripped by heat and/or inert gas to recover adsorbed naphthenes, and then returned to the tower after having been re-treated with the selective solvent, if necessary. It will als be ob- Vious that product streams-can'be returned to the tower as "refiuX in order to obtain greater purity, if desired. The invention can be practiced on normally liquid hydrocarbons such as light naphtha, heavy naphtha, kerosene, light and heavy heating oils and lubricating oils, or fractions thereof. It is generally preferred to employ relatively narrow fractions as feedstocks, and to carry out the adsorption step at a temperature in the range from about F. to about 150 F., preferably 75 F. to 140 F.

The nature and objects of the present invention having been thus described and illustrated,

' what is claimed as new and useful and is desired to be secured by Letters Patent is:

1. A process for separating naphthenes from paraffin hydrocarbons which comprises contacting at room temperature a hydrocarbon feedstock boiling from to 250 F. containing only parafiins and naphthenes with silica gel which has been previously contacted with a liquid selected from the group consisting of ethylene glycol, mono-methyl ether of diethylene glycol, aniline, acetone, isopropyl alcohol, dimethoxytetraethylene glycol and methoxytrigylcol.

2. Process according to claim 1 in which the material used to pretreat the silica gel is ethylene glycol.

3. Process according to claim 1 in which the material used to pretreat the silica gel is the monoethyl ether of diethylene glycol.

4. Process according to claim 1 in which the material used to pretreat the silica gel is aniline.

5. Process according to claim 1 in which the material used to pretreat the silica gel is acetone.

6. Process according to claim 1 in which the material used to pretreat the silica gel is isopropyl alcohol.

FREDRICK L. JONACH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,425,535 Hibshman Aug. 12, 1947 2,464,931 Hirschler Mar. 22, 1949 2,487,804 Hermanson Nov. 15, 1949 FOREIGN PATENTS Number Country Date 456,958 Great Britain Nov. 18, 1936 

1. A PROCESS FOR SEPARATING NAPHTHENES FROM PARAFFIN HYDROCARBONS WHICH COMPRISES CONTACTING AT ROOM TEMPERATURE A HYDROCARBON FEEDSTOCK BOILING FROM 115* TO 250* F. CONTAINING ONLY PARAFFINS AND NAPHTHENES WITH SILICA GEL WHICH HAS BEEN PREVIOUSLY CONTACTED WITH A LIQUID SELECTED FROM THE GROUP CONSISTING OF ETHYLENE GLYCOL, MOMO-METHYL ETHER OF DIETHYLENE GLYCOL, ANILINE ACETONE, ISOPROPYL ALCOHOL, DIMETHOXYTETRAETHYLENE GLYCOL AND METHOXYTRIGYLCOL. 